Filter.



G. SPENOB.

FILTER.

APPLICATION FILED AUG. 16, 1913.

1,1 1 1,275. Patented Sept. 22, 1914.

3 SHEETSSHEET 2.

wi limazoae G. SPENOB.

FILTER.

APPLICATION FILED AUG 16, 1913.

Patented Sept. 22, 1914.

3 SHEBTS-SHEET 3.

marl 111111 mue mto c /q Lin moses GEORGE SPENCE, OF MEXICO, MELIICO.

FILTER.

Specification of Letters Patent.

Patented Sept. 22, 1914.

Application filed August 16, 1913. Serial N 0. 785,070.

tary drum filters of that type in which an annular body is circumferentially provided with a filtering medium and the material under treatment is drawn into the drum compartments by means of a vacuum created in the drum, as the drum is rotated.

Numerous disadvantages arising from the drum filters now in use are sought to be overcome in the present invention. As now constructed, drum type filters usually consist of a large cylinder having a peripheral perforated screen over which is fastened a continuous filter cloth, the latter being secured by many circumferential wraps or turns of a wire or other material, the Winding pursuing a spiral course over the drum surface. Owing to the size of the drum, and the necessarily tedious process of covering the latter, as above described, it is hardly possible to recover a drum in less than a day, and often longer if the attendant is not expert in replacing the cloth. During the time which is thus being consumed, the machine is at a stand-still and unless the mill is provided with storage tanks for solutions, pulp (the finely ground ore which, in the cyanid process it is necessary to separate from the value-carrying solutions), and the other necessary fluid bodies, it is often necessary to close down the whole mill. Changes of the filter-cloth are frequent, either because the cloth gets dirty and requires an acid wash, or because the cloth is torn by the scraper, and for the still further reason that the life of a cloth is not very long under any circumstances. Unless the winding is of practically the same tension throughout, a condition which it is difficult to obtain, the cloth will bulge in places after a time, when compressed air is admitted, and be cut by the ed'ge of the scraper. It is difiicult also to prevent the compartment under compressed air to discharge its contents into the adjacent compartment, which is under a I vacuum. So serious is this difiiculty in some drum filters, that compressed air is suppressed and the cake is dislodged sim 1y by means of the scraper. This is not su cient to insure the cloth being properly cleaned however, before further immersion in the tank. Unless the filter cloth is easily removable, part of the mill-men to put off the inevitable hour of replacement until the last moment, with the consequence that as the cloth gets dirty and clogged, the capacity of the machine is increasingly inefficient.

With the above introductory remarks, the object of the present invention will be stated generally as being to provide a drum filter in which the disadvantage of rewinding the cloth is dispensed with, and in which it is possible to renew the filter clot-h completely without such a large percentage of time loss. It is likewise possible with the improved device to renew damaged sections without the removal or replacement of the whole cloth or circumferential covering, and for this purpose, the drum consists, generally of a supporting frame forming a circumferential body and peripherally provided with a plurality of removable filter frames, sections or compartments, each compartment or tray complising an independent filtering device, and having its separate cover, yet forming with the adjacent sections or trays on the frame, a substantially continuous peripheral filtering surface.

A further advantage and object of the invention consists in constructing a drum filter which, while possessing the same or greater capacity than drums heretofore used, will also be more practical and economical in build, having less weight and material in its construction than any filter drum known to me.

Another object consists in providing an eflicient system of withdrawing liquids from the sections of the drum, and for feeding compressed air and creating the vacuum in said sections; said system working in with the drum construction in the novel manner hereinafter set forth.

Another object consists in the particular unitary structure of the trays or sections, whereby each tray or section in itself becomes an eflicient filtering device.

Further, it is an object to construct a drum filter of such a character that it is readily and easily erected or dismounted at the mine and all parts of which are easily there is a strong liability on the transported within mule-back limits, and

a after appear.

to this may be added the fact that the material used in the construction of the apparatus is generally of a standard character,

and capable of ready repair or replacement.

" tion, of the assembled drum, Fig. 2 is a fragmentary view of the drum, showing one of the filter sections, compartments or trays in plan, Fig. 3 is a sectional view through the drum structure and one of the trays, Fig. 4 is a view on the line -l4 of Fig. 3, Fig. 5 is a view on the line 5-5 of Fig. 3, and Fig. 6 is a view on the line 66 of Fig. 3.

In Fig. 1 the assembled drum, having a full complement of removable trays or sections A is shown. In the drum as now constructed sixteen trays or sections are found to constitute a satisfactory number, though, of course, the number can be varied to suit the conditions of size of drum or more adaptable size of tray. The drum is carried by an axle B, mounted in trunnions C and D (Fig. 3), which are in turn mounted in bearings and (Z. Said trunnions C and D also serve a further purpose as will herein- At the middle point of the axle B is mounted a third piece E, and from each of the trunnions C, D, and E extend the radiating spokes F, G and H. Said spokes F, G and H respectively engage and rigidly support the annular rims f, g and h. The outer rims f and h are formed out of outturned angle irons, while the intermediate rim 9 is formed of a T bar, and serves together with spokes G, to strengthen and rigidly brace the whole structure. As a further trussing device and providing a means to center and adjust the whole frame-work the rods I and J, having the intermediate turnbuckles z and j are crossed from the rim 9 to the trunnions C and D, respectively where they are suitably secured. As best seen in Figs. 4: and the spokes F and H are threaded into blocks K and L, which are in turn bolted to the rims f and h or otherwise suitably secured thereto.

Mounted upon the outer rims f and h of the drum are the reversed or inverted annular angle iron bars M and N, and across the drum at regular intervals, to form seats for the trays or sections of the filter, and supported by the bars M and N are the transverse bars 0, said bars 0 co'ciperating with the bars M and N to inclose comparatively deep rectangular recesses, in suitable number to receive all of the trays.

Each of the trays A consists of a rectangular frame, substantially constructed ofwood or other suitable material and having secured therein the sheet-metal bottom a. Said bottom is provided with upturned edges which are bolted, riveted or otherwise fastened to the i'nside edges of said frame and is also bolted to the transverse members a of the frame, so that a solid receptacle is formed. Bolt holes P are provided at each end of the tray A, which register withsimilar holes 70, bored through the section seats at each end thereof, (Figs. 4 and 5), and through these openings are projected suitable securing devices for removably fastening the trays or sections in place on the drum frame.

Extending over the top of each section or tray A, and bent down and under the sides and ends thereof, for suitable fastening, is the perforated plate or wire screening Q. This screening forms a base for the covering or filter cloth R, which is stretched smoothly over the screening and folded down and under the sides of the frame of the section with the screen covering, and is secured by suitable wrappings and by being clamped under the ends and sides of the section when the latter is bolted in its place on the frame.

This is most clearly shown in Figs. 4 and 5,

where theunder sides of the ends and sides of the trays are shown to be rabbeted to receive the edges of the screening and cloth, forming an airtight joint.

As hereinbefore stated, the spokes F and H serve a double purpose, one for supporting the drum periphery, and the other being to act as conduits for drainage, furnishing compressed air and creating the vacuum in the trays. The trunnions C and D are provided with a plurality of longitudinal passages or ports 0' and d, which are connected with the pipe-spokes F and H and are of a number in each trunnion corresponding to the number of trays constituting a complement for the drum in use. The compressed air is introduced into the sections through the pipes or spokes F, which enter the trays at middle points of the ends and communicate with ports or passages f which are cored out of the frame end of the sections. A seat' is formed on the under side of each of such ends, concentric with the lower end of the port, said seat being. occupied by a washer or gasket S againstwhich the end of the spoke or pipe F bears to form an air and water-tight joint between the pipe and tray, as the latter is bolted down to the drum. A similar condition exists at the opposite end of the tray, where the pipe or spoke H connecting with the exhausting port h of the tray A, bears against a gasket seated in the same manner as the one at the bottom of the compressed air port. It will be noted that the ports or passages d in the .trunnion D are branched and connect with smaller pipes H which are extended to and connect with the trays A at one corner, where they act as drainage tubes, to carry off the solution from the trays, the drainage ports being located to cooperate with the slant of the tray bottoms to effectively deliver all of the liquid from the tray. One defect of former drum filters has been the ineflective manner in which the solution drawn into the filter compartments has been taken therefrom, it often occurring that the solution has passed back through the filter cloth under action of the compressed air blast, after the vacuum has been dispelled.

The operativeness of the trays'can best be understood from an examination of the views of Figs. 4, 5 and 6, which show in detail the various parts. In Fig. 5 the compressed air inlet tube or spoke F is tightly compressed against the gasket S at the lower end of the inlet port 8, by means of the bolts 79 passing through the bolt-holes Band ;0 in the section frame and the rim f respectively. In Fig. 4, similar bolts p compress the spokes H and H against the gaskets S and S of the ports 8' and s" respectively, the pipe or spoke H being connected through the trunnion to a suitable vacuum pump for producing suitable vacuum in the tray A, and the pipe H being adapted to drain all of the solution from the tray A when the latter has become tilted by the rotation of the drmn to so cooperate with the inclined bottom of the tray as to cause all of the solution to pass from all parts of the tray through the'passages 7' in the cross p1eces a.

The trunnions C and D are constructed so that the passages'c and cl communicate with the outside faces of the trunnions, where they are suitably provided with disk valves for consecutively opening the proper ports for establishing communication between the vacuum pump and the compressed air supply source at the proper times, so that alternately the vacuum pump may draw a quantity of liquid into the submerged compartment, through the cloth filterand screen,

- and after the tray has passed out of the tank of material which is being filtered, the compressed air may be forced into the tray and low the cake adhering to the cloth oil the outer surface thereof, the compressed air acting at the same time to help the solution to pass out of the ducts or pipes H. i In preparing the trays for use on the drum, the cloth is-secured on the frame-and screening by wrappings as hereinbefore set forth and by-stitching to the meshes of the screening, and an air tight joint around its edges is secured by lapping the cloth under the frame of the section and drawing it tight as the bolts 22 are drawn up to place. VVhen .1t is necessary to renew the cloth on any one part of the drum, only the sections effected are removed and replaced by new any appreciable delay in the operation of the machine. The drum is adapted to be suspended over a tank of the pyramid type, not shown in this application, and revolves once in five or six minutes, and the vacuum and compressed air valves are so arranged that the compressed air port is opened slightly in advance of the closing of the vacuum valve, so as to blow out the solution remaining in the vacuum spoke and prevent its return to the tray.

What I cl'aim and desire to secure by Letters Patent of the United States is 1. In a vacuum filter of the revolving drum type, the combination with the drum periphery and the supporting axle, of vacuum spokes on one side of the drum and compressed air spokes on the other side of said drum, a series of interchangeable, detachable, transversely-disposed filter trays or sections supported on said periphery, and trunnions within which the axle is mounted, said trunnions being formed with longitudmal ports communicating with said spokes.

2. In a vacuum filter of the revolving drum type, the combination with the drumsupporting axle, of vacuum spokes on one side of the drum, compressed air spokes on the other side of said drum, a series of' detachable transversely-disposed trays or sections having their ends resting on the outside rims of the drum, and trunnions w1thin which said axle is mounted formed with longitudinal passages communicating w1th said spokes;

3. In a vacuum filter of the revolv ng type, a system of conduits for withdrawing the solutions from the lower end of the tray and .admitting compressed air to the interior of same at the upper end, said condult's comprising channeled trunnlons and the spokes of the drum supporting the two outside rims of the same, on which the ends of the trays rest and communicate with said spokes for the purposes stated.

In testimony whereof I have afiixed ,my signature in presence of tw o witnesses.

GEORGE SPENCE.

Witnesses: JOHN A. VAN HORN, NQA. Vnsr. 

